More thoughts on gain settings

This is a little late to add to George's topic, so I'm starting a new 
thread...

To summarize, the classic method seems to be to get as much gain as you
can 
out of the first preamp stage to get a good S/N ratio, with enough
headroom, 
and then set the following stages to maintian this all the way to the amp.

Not going into what is enough headroom or how you determine it, this is
the 
jist of the idea.

Another school of thought that I've been exposed to is to optimise the 
levels for unity gain after the the first stage - i.e get as much gain as 
you *need* from the first stage so you don't have to attenuate or amplify 
the level at a following stage. It's based on the idea that idea that 
changing the gain level always has some detrimental side effects, so get
as 
close as you can at the first stage and then try to keep the following 
stages close to unity gain. In practice this frequently means reducing the

trims to keep the faders near zero.

Is there any validity to it is this just another garbage idea that I
picked 
up decades ago? The electronics have improved so much (or maybe I'm just 
using better gear) that the noise floor of the source signal is much
higher 
than anything in the board. I'm just not convinced that unity gain in a 
preamp stage is the same as a 'wire without gain'.

Thanks in advance,
Sean

*just to clarify my terms - by preamp stage I mean any in-line amplifier 
circuit intended to drive a following circuit, and not a speaker.